Adjustable stool



May 7, i968 E. E. FRITZ ETAL 3,381,925

ADJUSTABLE STOOL Filed OCT. 20, 196

INVENTORS ammo E. FR/ rz flic/*Ms H. Fm r2 United States Patent O3,381,926 ADJUSTABLE STOOL Edward E. Fritz, 201 Fernwood Drive, andThomas A. Fi7tz, 221 Fernvvood Drive, both of Evansville, Ind. 4 11Filed Oct. 20, 1966, Ser. No. 588,226 5 Claims. (Cl. 248-404) Thepresent invention relates to an adjustable stool, and more particularlyto a new and novel mechanism for controlling the height of the stoolseat.

As is known, it is desirable to be able to change the height of a stoolseat automatically, particularly in the instance of a stool used bypersonnel in a medical or dental ofiice. Such ready seat heightadjustment results in optimum examination and/or treatment of a patient,as well as a convenience, and even more so when accomplished by footcontrol, as in the present invention.

By virtue of the invention at hand, the inventors herein have provided anew and novel control mechanism for adjusting the height of a seatforming part of a stool which may have application in a dental ormedical oice. The seat of the inventors new and novel adjustable stoolis controlled by foot operation, meaning that the users hands are freeto work, as well as maintained in a sanitary condition.

Broadly, the inventors control mechanism is operated through a hydraulicarrangement, where, with the opening of a control valve, the seat of thestool moves downwardly because of the weight of a person thereon, or, inthe alternative, when unoccupied, moves upwardly due to the compressionof a spring which pressures hydraulic fluid by means of a piston. Theinstant control mechanism is representative of a minimum number ofoperative components, reecting in manufacturing and maintenanceeconomies, in addition to highly desirable end results.

Accordingly, the principal object of the present invention is to providea new and novel adjustable stool.

Another object of the present invention is to provide a new and novelcontrol mechanism for adjusting the height of a seat of a stool.

A further and more general object of the present invention is to providea foot operated control mechanism for adjusting the height of a stoolseat which is positive in operation; which is readily manufactured;which requires a minimum number of operative components; which permitsoperation at a convenience not at all present heretofore; and, whichretiects a highly sturdy structural arrangement.

Other objects and a better understanding of the present invention willbecome more apparent from the following description, taken inconjunction with the accompanying drawing, wherein FIG. 1 is a view inelevation, partly fragmentary, partly in phantom, and partly in verticalsection, showing the height operating mechanism for the inventors newand novel adjustable stool; and,

FIG. 2 is a fragmentary bottom view of the lever arrangement forpermitting foot control of the mechanism at hand.

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiment illustrated inthe drawing and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring now to the figures, the height control mechanism 10 for theinventors new and novel adjustable stool is shown in heavy lines, whilethe mobile base framework, the seat and a portion of the back are shownin phantom lines, all of the latter being conventional and shown forreasons of total impression clarity. In any event, the aforesaid mobilebase framework supports an upstanding centrally disposed outer tube 12having at opposite ends, and threadedly secured thereto, an upper cap 14and a lower cap 16, the latter being threadedly positioned to the baseframework by a locking member 15. Disposed Within the outer tube 12 andpositioned by an abutment on the upper cap 14 and received within anopening in the lower cap 16 is an inner tube 17, the latter positioninga shaft 19 which extends downwardly from the bottom of the stool seat.

An inner piston 20 is disposed at the lower free end of the shaft 19 andis movable therewith, typically including seal members 22, such asO-rings, for example, around the outer surface thereof. An outer piston30, also including various seal members 32, is disposed in the spacebetween the inner tube 17 and the outer tube 12, where a heavy dutycompression member 24, such as a spring, for example, completes thespace between the outer piston 30 and the upper cap 14, being seated onsuch outer piston 30. The relative positioning of the inner piston 20`and the outer piston 30 will be discussed more fully herebelow.

A control Valve 35 is positioned, typically, on the bottom surface ofthe lower cap 16, being conventional in 'form and permitting selectivecommunication between a longitudinal passageway 16a at one portion ofthe lower cap 16 and another longitudinal passageway 16b disposed atanother portion of the lower cap 16. More specifically, passageway 16acommunicates with the space within the inner tube 17 below the innerpiston 20, while passageway 16b communicates with the space above thelower cap 16 and below the outer piston 30. For purposes of effectiveoperation, another seal member 16C is employed around the outer surfaceof the iower cap 16.

The control valve 35 includes a slidable plunger 35a normally urged byspring means (mostly not shown) into the position of FIG. 1, i.e. notpermitting any communicatioin between passageways 16a and 16b. In orderto afford such communication, when desired, a foot control arrangementis provided comprising one or more foot engaged members 40 extendingupwardly from the base, the lower ends of each of which engage controlarms 41, the latter being secured to a transverse member 42 positionedon the undersurface of the base by brackets 42a (see FIG. 2).

An actuating member 45 angles downwardly from the transverse member 42,and has a portion thereof which contacts a control button 35boperatively connecting the plunger 35a of the control valve 35. In otherwords, rby depressing the foot engaged member 40, the control arms 41,and, hence, the transverse member 42, pivot, forcing the control button35b from right to left in FIG. l through movement of the actuatingmember 45, and permitting communication between passageways 16a and 16bthrough a path created within the control valve 35.

In order to control the height of the seat, a hydraulic fluid, such as alightweight oil, for example, is introduced into the space within theinner tube 17 below the inner piston 20. When the seat of the stool isoccupied by a person, and when the foot engaged member 40 is -moveddownwardly to permit operation of the control valve 35, the hydraulicfiuid moves downwardly through passageway 16a, the path within thecontrol valve 35, and upwardly through the passageway 16b into the spacebetween the inner tube 17 and the outer tube 12 above the lower cap 16and below the outer piston 30, causing the outer piston 3() to moveupwardly and, hence, to

compress the spring 24. When the user reaches the desired height, thefoot engaged member 40 is released to lock the stool seat at suchposition.

On the other hand, when it is desired to elevate or raise the height ofthe seat, and with the seat unoccupied, the foot engaged member `40 isdepressed to again operate the control valve 35, creating a path betweenpassageways 16a and 16b. In this instance, however, the compressedspring 24 forces the outer piston 30 downwardly and, hence, thehydraulic iluid through passageway 16h, the path within the controlvalve 35, and through the passageway 16a into the space within the innertube i7 below the inner piston 20, making the inner piston 20 with itsstool seat supporting shaft 19 move upwardly. Again, as soon as thedesired height is achieved, such height may be maintained by releasingthe foot engaged member 49.

From the preceding, it should lbe apparent that the inventors hereinhave provided a new and novel approach for controlling the height of astool. Positive action is guaranteed, and ready use thereof isachievable by the operator. Not only are a minimum number of componentsutilized, but a sturdy structure is afforded the over-all mechanism.

The adjustable stool described above is, of course, susceptible tovarious changes within the spirit of the invention. Obviously, otherlfoot operated linkage arrangements might be devised, as well asover-all proportioning varied. Thus, the above description should beconsidered illustrative and not as limiting the scope of the followingclaims:

We claim:

1. 4A height adjusting mechanism for a stool having a base framework anda seat comprising spaced-apart hol low inner and outer members disposedon said base framework, cap Imembers at opposite ends of said hollowinner and outer members, an inner seat mounting piston slidable withinsaid hollow inner member, an outer piston slidable in the space betweensaid hollow inner member and said hollow outer member, compression meansurging said outer piston in a downward direction, cavities containing aliquid in said hollow inner member below said inner piston and in thespace between said hollow inner member and said hollow outer memberbelow said outer piston, passageways through said cap member at thelower ends of said hollow inner and outer members communicating withsaid cavities, and control mechanism selectively permittingcommunication between said passageways for seat height adjustment.

2. The height adjusting mechanism of claim 1 where said compressionmeans is a spring.

3. The height adjusting mechanism of claim 1 where said controllmechanism is a valve, and where said valve has a movable element toselectively provide a path between said passageways.

4. The height adjusting mechanism of claim 1 where said controlmechanism is foot-operated.

5. The height adjusting mechanism of claim 1 where a foot-operatedlinkage system is provided for said control mechanism comprising afoot-engageable element disposed on said base framework, an intermediatemember rotatably mounted on the undersurface of said base framework andhaving an extending arm driven by said footengageable element, and apower arm on said intermediate member selectively operating said controlmechamsm.

References Cited UNITED STATES PATENTS 557,847 4/1896 Mann 248--4042,237,915 4/1941 Routson 267-34 2,586,442 2/ 1952 Seagren. 2,636,3484/1953 Murray 10S-147 X 3,143,332 8/1964 Watlington 248-404 3,311,4073/1967 Horie 297-347 X 3,339,873 9/1967 Hale 248-404 JAMES T. MCCALL,Primary Examiner.

1. A HEIGHT ADJUSTING MECHANISM FOR A STOOL HAVING A BASE FRAMEWORK ANDA SEAT COMPRISING SPACED-APART HOLLOW INNER AND OUTER MEMBERS DISPOSEDON SAID BASE FRAMEWORK, CAP MEMBERS AT OPPOSITE ENDS OF SAID HOLLOWINNER AND OUTER MEMBERS, AN INNER SEAT MOUNTING PISTON SLIDABLE WITHINSAID HOLLOW INNER MEMBER, AN OUTER PISTON SLIDABLE IN THE SPACE BETWEENSAID HOLLOW INNER MEMBER AND SAID HOLLOW OUTER MEMBER, COMPRESSION MEANSURGING SAID OUTER PISTON IN A DOWNWARD DIRECTION, CAVITIES CONTAINING ALIQUID IN SAID HOLLOW INNER MEMBER BELOW SAID INNER PISTON AND IN THESPACE BETWEEN SAID HOLLOW INNER MEMBER AND SAID HOLLOW OUTER MEMBERBELOW SAID OUTER PISTON, PASSAGEWAYS THROUGH SAID CAP MEMBER AT THELOWER ENDS OF SAID HOLLOW INNER AND OUTER MEMBERS COMMUNICATING WITHSAID CAVITIES, AND CONTROL MECHANISM SELECTIVELY PERMITTINGCOMMUNICATION BETWEEN SAID PASSAGEWAYS FOR SEAT HEIGHT ADJUSTMENT.